(1) Generically, open source refers to a program in which the source code is available to the general public for use and/or modification from its original design free of charge, i.e., open. Open source code is typically created as a collaborative effort in which programmers improve upon the code and share the changes within the community. Open source sprouted in the technological community as a response to proprietary software owned by corporations.

(2) A certification standard issued by the Open Source Initiative (OSI) that indicates that the source code of a computer program is made available free of charge to the general public. The rationale for this movement is that a larger group of programmers not concerned with proprietary ownership or financial gain will produce a more useful and bug -free product for everyone to use. The concept relies on peer review to find and eliminate bugs in the program code, a process which commercially developed and packaged programs do not utilize. Programmers on the Internet read, redistribute and modify the source code, forcing an expedient evolution of the product. The process of eliminating bugs and improving the software happens at a much quicker rate than through the traditional development channels of commercial software as the information is shared throughout the open source community and does not originate and channel through a corporation's research and development cogs.

OSI dictates that in order to be considered "OSI Certified" a product must meet the following criteria:

The author or holder of the license of the source code cannot collect royalties on the distribution of the program

The distributed program must make the source code accessible to the user

The author must allow modifications and derivations of the work under the program's original name

No person, group or field of endeavor can be denied access to the program

The rights attached to the program must not depend on the program's being part of a particular software distribution

The licensed software cannot place restrictions on other software that is distributed with it.